The present invention relates to a removable cap for the inwardly directed end of a vertical post of a set of metal frames forming shelving. The shelving is very often seen in “big box” stores, warehouse-styled clubs, and, of course, within warehouses, all to store and/or display merchandise. The caps are molded plastic inserts that are forced into the holes of the opposed vertical posts (where shelf brackets elements are otherwise inserted) and block off the exposed holes on the vertical posts from fingers being accidentally inserted and also from dust and other accumulation gaining entry within the hollow vertical chamber of the posts. The back of the plastic cap is provided with at least two pairs of opposed resilient ears which are capable of being squeezed together as the face on the cap is pressed onto the posts. When the ears pass through the holes of the vertical posts their resiliency allows them first to compress and pass between the edges of the hole and then when the maximum distance between opposed ears of a pair pass through the hole, the resiliency “pops” them back to their original spread apart configuration. The ears are thus held within the posts and the cap to the face of the post, i.e., the cap is held flush against the outside wall (yet facing inwardly) of the posts. This secures the cap to the post. Also, the cap is provided with a series of vertically spaced knock-out tabs which are aligned with the holes of the vertical posts of the shelving system. Only those tabs which are aligned with the holes of the post which are meant to support the shelf brackets of the shelving system are removed from the cap. Thus, the other tabs remain and block off the other open holes of the vertical posts. This prevents little fingers (children often shop with their parents in the “big box” stores) and dust and debris from accumulating within the hollow chamber of the vertical posts since access is blocked thereto by the closing off of the holes of the post by the cap and the remaining tabs, except those holes of the post and the cap which are aligned and unblocked for receipt of the shelf brackets.